The invention relates of a method and an arrangement for detecting the misuse of the call forwarding service in a mobile communication system, the method comprising the steps of: activating call forwarding for routing a call addressed to a mobile subscriber to a forwarding number supplied by the mobile subscriber, and changing the forwarding number by registering call forwarding to another number.
In addition to speech and data transmission, modern mobile communication systems provide subscribers with a plurality of supplementary facilities. During the last few years, the basic services defined by the standards have been taken into use, and the supply of more developed services based on the intelligent network architecture has continued to increase.
One of the most important supplementary facilities of mobile communication systems is call forwarding which a mobile subscriber can activate. Various call forwarding facilities may be chosen. In unconditional call forwarding, the mobile subscriber gives a call forwarding number to which a mobile terminating call is always forwarded. In conditional call forwarding, the mobile subscriber gives a number or numbers to which a mobile terminating call is forwarded if the mobile station is busy, disconnected from the network or when the mobile subscriber does not reply within a specified period of time. Call forwarding may also be defined service-specifically, whereby speech, data and facsimiles are each routed to a different number.
With services becoming more general, the operators have faced situations when services are misused, either for purposes of vandalism or for economic interest. It has been observed that even the call forwarding facility can be misused. In such cases a mobile subscriber offers to other parties the chance to make expensive call via his number, bills the callers himself, and fails to pay his own bills. Before an operator can reliably detect the misuse, the mobile subscriber may have caused significant damage.
It is the object of the present invention to provide a means for detecting the above described misuse of the call forwarding facility as quickly as possible, and for implementing continuous control of call forwarding facilities.
This object is achieved with a method of the type described in the preamble, characterized in that the number of call forwarding registrations is counted subscriber-specifically, and an alarm is generated when the number of call forwarding registrations exceeds a predetermined maximum value during a predetermined period of time.
The invention is based on the idea that subscriber-specific counters counting the number of call forwarding registrations activated by a subscriber are arranged in the mobile communication system, preferably in a subscriber data base. If the number of call forwarding registrations rises remarkably high, it may be suspected that the mobile subscriber is misusing his subscriber line, and the operator is alerted. The operator is also provided with reports on the call forwarding functions of the subscribers at given intervals, for example in the order of the number of issued call forwarding registrations, whereby the operator quickly notices which users have to be observed regarding their payment behaviour.
The invention provides an efficient means for preventing intentional misuse of the call forwarding facility, and, in addition to maintaining continuous operation, for rapidly screening the cases where misuse may be suspected.